Detection Of Trace Water Research Articles

Carbon dots for efficient detection of water content in organic solvents

The trace amount of water in organic solvents can affect the progress of chemical reactions, which will adversely affect chemical production in many industries, resulting in a doubling of costs. In this work, carbon dots (CDs) with abundant polar groups were synthesized by a simple one-step hydrothermal method. The prepared CDs showed superior dispersibility and fluorescence performance compared to the CDs that have been reported for the detection of water content in organic solvents. It can realize the fluorescence detection of trace water in several water-soluble organic solvents such as N,N-dimethylformamide, ethanol and methanol with wide linear range (0 %–100 %) and high sensitivity. This will provide a powerful tool for the rapid detection of water content in organic solvents in chemical production.

Multi-stimuli-responsive cyanostilbene derivatives: Their fluorescent and mechanochromic properties, and potential application in water sensing and anti-counterfeiting

In recent years, aggregation-induced emission luminogens (AIEgens) have witnessed numerous groundbreaking advances in fundamental theoretical research and functional applications. Notably, stimuli-responsive AIEgens have achieved remarkable results, demonstrating immense potential for application in various fields such as chemistry, materials science, biology, and medicine. Herein, two multi-stimuli-responsive cyanostilbene derivatives TPE-CNTPA and PH-CNTPA were synthesized by introducing tetraphenylethylene (TPE) and trifluoromethyl groups, respectively. Primarily, under the combined mechanism of aggregation-induced emission (AIE) and twisted intramolecular charge transfer (TICT), TPE-CNTPA and PH-CNTPA exhibit “on-off-on” fluorescent emission characteristics in solution. Secondly, under 365 nm ultraviolet light irradiation, the photo-induced isomerization of PH-CNTPA causes changes in photophysical property, demonstrating its responsiveness to ultraviolet light. In addition, TPE-CNTPA and PH-CNTPA exhibit high-contrast mechanochromic properties, providing broader possibilities for their potential applications in various fields. Moreover, owing to the unique fluorescence emission characteristics, TPE-CNTPA and PH-CNTP have enormous potential for application in the field of encryption anti-counterfeiting. Besides, PH-CNTPA can be utilized for the detection of trace water in single or mixed solvents, demonstrating outstanding sensitivity and anti-interference properties in different solvents. This research work reveals the potential in the fields of water sensing and anti-counterfeiting for these two multi-stimuli-responsive compounds.

Fluorion-deprotonated fluorescent sensor for the highly sensitivity detection of trace water in chemical reagents and application in inkless writing

A simple diphenylimidazole-based colorimetric and fluorescent sensor (DIB) was successfully synthesized by one step reaction. DIB exhibited excellent selectivity and sensitivity for F- over various other anions with fluorescence enhancement effect. The limit of detection of DIB towards F- was evaluated to be 9.18 × 10-8 M. A plausible sensing mechanism of DIB towards F- had been proposed on the basis of spectral analysis and 1H NMR titration experiments, which the results suggested that the recognition process could be attributed to the deprotonation of imidazole group. Interestingly, the F- induced deprotonation system of DIB·F could be employed as reversible sensor for trace water with high sensitivity and instant response. The color change easily recognized by the naked eye and low limit of detection (0.0022 %) improved the detection performance of DIB·F for water. Importantly, the DIB·F system had been successfully applied for the quantitative analysis of water content in experimental chemical reagents. In addition, sensor DIB and DIB·F-incorporated filter papers could be utilized as inkless writing display device for F- and water detection, respectively, with reusability.

A novel fluorescent indicator-based fluorene derivative for rapid and visual trace water sensing.

Fluorene nucleus derivatives show great potential for building outstanding fluorescence probes. In this paper, a novel fluorescent probe was developed by reacting with fluorene core with azacyclobutane, which exhibits typical solvation chromogenic effect in solvent. The fluorescence of the probe quenched in highly polar solvent. Based on this phenomenon, a novel fluorescence system for trace water was constructed. The response of this probe was fast (30 s) and sensitive for the detection of trace water in organic solvents, and the detection limit of water content in DMSO reached 0.13%. In addition, the probe can also be made as a test strip combined with homemade portable device and a smartphone for rapid detection of trace water. The luminescence mechanism of the probe is theoretically calculated based on time-contained density functional theory (TDDFT). To showcase its practicality, it has been applied for the detection of trace water in honey and alcohol by dipstick. This method provides a new idea for designing efficient fluorescent probes based on dipstick and mobile phone rapid detection.

Lead-Free Antimony-Based Perovskite Nanocrystals as a Fluorescent Nanoprobe for the Turn-On Detection of Trace Water in Organic Solvents

Lead-Free Antimony-Based Perovskite Nanocrystals as a Fluorescent Nanoprobe for the Turn-On Detection of Trace Water in Organic Solvents

Eu3+-Doped aluminum Metal-Organic Frameworks: A versatile platform for ratiometric detection of histidine and Water, and visible fingerprint identification

Ratiometric fluorescent sensors possess inherent self-calibration features that enable the mitigation of interference from factors unrelated to the analysis. This characteristic results in heightened sensitivity and more pronounced visual detection during qualitative and quantitative analytical processes. A ratiometric fluorescence probe Eu/Al-MOF has been successfully prepared via Eu3+ doped aluminum metal − organic frameworks. Upon introducing histidine, the fluorescence intensity of Eu3+ showed a noteworthy increase, whereas the intensity originating from the ligand decreased owing to enhancing energy transfer from the ligand to Eu3+ ions in the probe. Eu/Al-MOF could detect histidine over a wider linear range of 0.1–400 μM and a lower detection limit of 0.04 μM. Besides, in the presence of water in organic solvents, the excited state of Eu3+ in the probe could be coupled with the O-H oscillation of water molecules, and the excited state energy from Eu3+ would be transferred to the water molecules so that only the fluorescence intensity of Eu3+ gradually decreased. Thus, the proportional detection of trace water could be realized. In ethanol and DMF, the detection range for water was 0.1–20 % and 0.5–20 %, respectively. Moreover, it was found that Eu/Al-MOF could efficiently achieve the visualization identification of fingerprints, providing the possibilities for applying the nano-sensor as a promising multifunctional fluorescence probe.

Excited-state intramolecular proton transfer (ESIPT) active interwoven polycatenated coordination polymer for selective detection of Al3+ and Ag+ ions along with water detection in less polar solvents.

The external stimuli-responsive excited-state intramolecular proton transfer (ESIPT) on/off mechanism is a unique and expedient sensing method that offers easy monitoring through the transition between dual and single-peak emissions. To avail this advantage of ESIPT-based sensing for selective metal ion detection and trace water detection, we have synthesized a 2,5-dihydroxyterephthalate (dht)-based interwoven polycatenated coordination polymer (1). The synthesized compound has been thoroughly characterized using single-crystal and powder X-ray diffraction techniques, along with other physicochemical methods. The synthesized compound exhibits a visual luminescence color change from faint yellow to bright green under UV irradiation in the presence of Al3+ ions. This change is attributed to a blue shift in fluorescence maxima of the keto form of the dht ligand in contact with Al3+ ions. Additionally, the material detects Ag+ ions through an ESIPT-off mechanism. These significant changes in ESIPT - blue shifting for Al3+ and ESIPT-off for Ag+ - start in just 1 mM aqueous solutions of these ions. Significantly, the ESIPT-off for Ag+ is evident even in the presence of other interfering ions. Beyond metal ion detection, this material also offers both qualitative and quantitative sensing of trace amounts of water in various polar organic solvents, such as ethanol (EtOH), tetrahydrofuran (THF), isopropanol (IPA), acetone, and acetonitrile (ACN), through the ESIPT-on/off phenomenon. The activated framework of compound 1 (1') can detect 2%, 4%, 4%, 3%, and 3% water in acetone, ACN, EtOH, IPA, and THF, respectively; through the conversion from a single to dual hump emission alteration. The respective ESIPT peak shift and ESIPT-on/off in the presence of metal ions and water is explained by the interaction between the host coordination polymer and guest analytes.

Luminescence turn-on sensor for the selective detection of trace water and methanol based on a Zn(ii) coordination polymer with 2,5-dihydroxyterephthalate.

A highly selective detection of trace water in organic solvents is urgently required for the chemical industry. In this work, the simple sonochemical method was used for producing a luminescent sensor, [Zn(H2dhtp)(2,2'-bpy)(H2O)]n (Zn-CP) (H2dhtp2- = 2,5-dihydroxyterephthalate and 2,2'-bpy = 2,2'-bipyridine). Zn-CP exhibits reversible thermally-induced and methanol-mediated structural transformation. Importantly, Zn-CP has exceptional water sensing performance in both dry methanol and dry ethanol, with high selectivity, wide linear ranges, and a low limit of detection (LOD) of 0.08% (v/v). Upon the incremental addition of water, the luminescent intensities enhanced and shifted, along with the emission color changing from green to greenish yellow. In addition, Zn-CP can detect methanol selectively through turn-on luminescence intensity with LODs of 0.28, 0.52, and 0.35% (v/v) in dry ethanol, dry n-propanol, and dry n-butanol, respectively. The excited-state proton transfer of linker H2dhtp2-via enol-keto tautomerism and collaboration with structural transformation could be attributed to the sensing mechanism.

A versatile sensor capable of ratiometric fluorescence detection of trace water and turn-on detection of Cu2+ modulating the binding interaction of a Cu(II) complex with BSA and DNA complemented by docking studies.

A fluorescent molecule, pyridine-coupled bis-anthracene (PBA), has been developed for the selective fluorescence turn-on detection of Cu2+. Interestingly, the ligand PBA also exhibited a red-shifted ratiometric fluorescence response in the presence of water. Thus, a ratiometric water sensor has been utilized as a selective fluorescence turn-on sensor for Cu2+, achieving a 10-fold enhancement in the fluorescence and quantum yield at 446 nm, with a lower detection limit of 0.358 μM and a binding constant of 1.3 × 106 M-1. For practical applications, sensor PBA can be used to detect Cu2+ in various types of soils like clay soil, field soil and sand. The interaction of the PBA-Cu(II) complex with transport proteins like bovine serum albumin (BSA) and ct-DNA has been investigated through fluorescence titration experiments. Additionally, the structural optimization of PBA and the PBA-Cu(II) complex has been demonstrated by DFT, and the interaction of the PBA-Cu(II) complex with BSA and ct-DNA has been analyzed using theoretical docking studies.

Visual detection of water content in liquor with near-infrared fluorescence sensor assisted by smartphone

Water content was an essential indicator in organic solvents, and it was necessary to develop a facile, cheap and readily available tool for the real-time, specifical and sensitive detection of water content. In this work, two novel D-π-A type near-infrared fluorescence sensors (DCM-1 and DCM-2) were designed and synthesized for the detection of trace water in organic solvents. DCM-1 and DCM-2 with solvent-dependent effects and large Stokes shift (>120 nm) showed good linear “intensity-to-content” relationships in four commonly-used organic solvents, and accomplished the ultra-fast and high-accuracy detection of the trace water in organic solvents. More importantly, a portable, fast, and accurate smartphone-assisted visual assay was designed for visual quantitative detection of the water content in organic solvents with a detection limit as low as 1.028 % v/v (e.g. in ethanol) and a wide detection range (0–60 % v/v). The smartphone-based visual assay was further applied to estimate the water content in disinfection alcohol and commercial liquor, which furnished a new strategy and broad prospects to achieve the accurate onsite detection of water content.

A fluorescence analysis model for assessing the water stability of porphyrinic metal−organic frameworks

Porphyrinic metal−organic frameworks (PMOFs) are a type of emerging porous material with potential applications in catalysis, biomedicine, and sensing. Despite their plentiful advantages, the applications of many PMOFs are ultimately limited by their water stability. The water stability of PMOFs is influenced by the coordination interactions between metal nodes and water molecules. In this work, based on the excellent photoluminescent properties of magnesium porphyrins, the interactions between water molecules and PMOFs with 15 metal nodes were studied and assessed by the fluorescence method. First, the ligand-to-metal charge transfer (LMCT) effect of these PMOFs was investigated. Subsequently, according to the fluorescence intensity and kinetic performance of PMOFs in ethanol with different water contents, a model for the water stability of PMOFs was established, and PMOFs were classified into three categories: water stable, relatively stable, and unstable. Finally, the water-sensitive magnesium node PMOF (MgTCPP-Mg) can serve as an excellent fluorescent probe for highly sensitive detection of trace water in organic media, particularly methanol, with detection limits as low as 0.0093 % (v/v). The establishment of this evaluation method and model helps researchers choose the appropriate PMOFs according to their needs.

A fluorescent and colorimetric probe for sensing trace water in ethanol and methanol based on an Al (III) complex of rhodamine-B Schiff base

A novel fluorescent and colorimetric probe was synthesized by the complexation of rhodamine-B Schiff base (L) and Al3+, which could be used to quickly detect trace water in ethanol and methanol. L showed a remarkable fluorescence enhancement and colorimetric responses upon reaction with Al3+. However, the intensity was significantly quenched upon the addition of trace water to the L-Al3+ solution, and the degree of quenching (1-I/I0) reached 94 % in ethanol and 88 % in methanol. Meanwhile, a significant change in color was also observed by the naked-eye from pink to colorless in the L-Al3+ solution. The fluorescent and colorimetric changes indicated that water could induce the dissociation of the L-Al3+ complex. Moreover, the L-Al3+ complex exhibited a good anti-interference fluorescence response to trace water in ethanol and methanol compared with other solvents. Also, the limit of detection (LOD) for ethanol and methanol were calculated as 0.0053 % v/v and 0.0080 % v/v respectively based on 3.3δ/k. Furthermore, the sensing mechanism of the L-Al3+ complex toward trace water was investigated by 1H NMR, HR-MS, FTIR, pH and AIE. Additionally, the L-Al3+ complex showed potential application in the detection of trace water in real ethanol methanol.

Rational design of push-pull fluorescent probe with extraordinary polarity sensitivity for VOCs chromic sensing and trace water detection

Developing fluorescent probes with excellent polarity sensitivity is still meaningful, but faces some challenges. Different from previous studies, this work focusses on modifying the π-bridge to improve the polarity-sensitivity, and found that taking quinoline with electron-deficient structure as π-bridge can significantly promote the intramolecular charge transfer from the electron-donor to electron-acceptor. Such modification on π-bridge endows fluorescent probe DQN with brilliant fluorescence which is highly sensitive to changes in environmental polarity. Based on it, the DQN-based test strips have been made for fast, visual, and reversible discrimination of four volatile organic compounds with varied polarities. Moreover, 92#, 95#, and 98# gasolines can be directly discriminated with DQN, showing completely different fluorescent colors under UV lamp. In addition, trace water in organic solvents can also be accurately detected, and their limits of detection are as low as 28 ppm (1,4-dioxane) and 16 ppm (tetrahydrofuran). In short, this work provides an inspirational perspective for the rational design of fluorescent probes with excellent polarity sensitivity for multifunctional applications.

Multi‐Responsive 0D Organic–Inorganic Hybrid Cuprous Bromides Constructed via Ultra‐Facile Approaches for Multimodal Luminescent Anti‐Counterfeiting

AbstractLuminescent anti‐counterfeiting has the advantages of high secrecy, low cost, flexible design, simple operation, and convenient light‐regulation of luminescent materials, which makes it easy to achieve high‐level multimodal anti‐counterfeiting. Here, zero‐dimensional (0D) organic–inorganic hybrid luminescent crystals (TPA)CuBr2 (TPA+ = [N(CH2CH2CH3)4]+) with multiple responses to ultraviolet (UV) light, water, and thermal stimulus are synthesized through an ultra‐facile approach for multimodal luminescent anti‐counterfeiting. Water‐sensitive (TPA)CuBr2 could transform into 0D (TPA)2Cu4Br6 upon external water stimulus, accompanied by the change of luminescence color from cyan to orange under UV light irradiation. Both (TPA)CuBr2 and (TPA)2Cu4Br6 exhibit high photoluminescence quantum yields, and long photoluminescence decay lifetimes. In addition, (TPA)CuBr2 and (TPA)2Cu4Br6 show reversible “on‐off” luminescence phenomena and excellent cycling stability under thermal stimulus. Exhilaratingly, multimodal anti‐counterfeiting luminescent labels with high‐security level could be fabricated based on the multiple responsive organic–inorganic hybrid cuprous bromides. Moreover, the test paper based on (TPA)CuBr2 could be fabricated for the detection of trace water in isopropanol. This work demonstrates the capabilities of (TPA)CuBr2 and (TPA)2Cu4Br6 as high‐security anti‐counterfeiting materials and luminescent sensors, which provides an important reference for exploring 0D metal halides for high‐level luminescent anti‐counterfeiting.

An emerging enol-based 1D covalent organic framework for trace water detection

The determination of trace water in organic solvents has been a long-standing research hotspot and is still evolving which requires further development. Ratiometric luminescent sensors with rapid response and accurate visualization of water assay based on porous materials are obviously prospective candidates for trace water detection, but remain a challenge. Herein, we firstly reported a novel one-dimensional (1D) covalent organic framework (COF, labeled as FZU-68) which was built from 2-hydroxyisophthalaldehyde (DIPh) and 1,3,6,8-tetra-(p-aminophenyl)-pyrene (PyTTA). The COF displays comparative high specific surface area, narrow pore size distribution and prominent chemical/thermal stability. Besides, its solid state displays a bright red emission at 606 nm. More impressively, due to a water-induced enol-keto isomerization in its structure, the fluorescence of FZU-68 quenched in response to trace amounts of water, which sustain the limit of detection (LOD) in acetonitrile (MeCN) up to 0.05% (v/v). Besides, FZU-68 could be utilized several times in the above trace water detection experiments. This study not only presents the feasibility of integrating heteroatoms and functional groups into 1D COFs, but also sheds light on the application prospects of COFs in the field of chemical sensing.

A smartphone-available colorimetric and near-infrared fluorescence sensor for trace amounts of water detection in highly polar organic solvents

In this work, we aimed to construct a sensitive and convenient sensor for trace amounts of water detection in highly polar organic solvents. We designed and synthesized four D-π-A structure sensors DTA-2QA-OH, TPA-2QA, TPA-2QA-OH, and TPA-4QA-OH by adjusting the electron donor and the linking site of the electron acceptor. The TPA-2QA-OH synthesized by connecting hydroxylated triphenylamine and quinolinium at position 2C can be used as a sensitivity sensor for trace amounts of water detection in highly polar organic solvents by using Na2HPO4 as a deprotonation reagent. TPA-2QA-OH can detect trace amounts of water in DMSO, MeOH, and EtOH in both colorimetric and near-infrared fluorescence modes. The significant color change of the sensing systems was captured by a smartphone and analyzed by using the PhotoMetrix APP to construct a standard curve between RGB values and water content in solvents. The detection limit of the sensor TPA-2QA-OH for trace amounts of water by using colorimetric, fluorescent, or smartphone methods were calculated as low as 0.0009% vol in DMSO, 0.0064% vol in MeOH, and 0.0014% vol in EtOH, respectively. For the first time, the influence of the connection site of quinolinium on the photophysical properties and detection performance of the sensor was found. The conjugation of the electron donor groups as well as the introduction of hydroxyl groups on the electron donor are important for the construction of D-π-A structure colorimetric and fluorescence ICT sensors for trace water detection in highly polar organic solvents.

Triboelectric Mechanism of Oil-Solid Interface Adopted for Self-Powered Insulating Oil Condition Monitoring.

The liquid-solid contact electrification mechanism has been explored in the aqueous solution system, but there are few systematic studies on oil-solid triboelectrification. Herein, an oil droplet triboelectric nanogenerator (Oil-droplet TENG) is designed as the probe to investigate the charge transfer properties at oil-solid interface. The charge transfer kinetics process is disclosed by the electrical signals produced, showing that the electron species initially predominated the oil-solid triboelectrification. The molecular structure and electronic properties of oil also affect triboelectric performance. Further, the charge transfer principle in multi-component liquid mixture during the electric double layer (EDL) development process is proposed to explain the component competition effect. As a proof of concept, a tubular-TENG is designed as a self-powered sensor for transformer oil trace water detection. The device demonstrates high water sensitivity with a detection limit of 10µL L-1 and a response range of 10-100µL L-1 . This work not only reveals the oil-solid triboelectric and charge transfer competition mechanism in EDL, but also open up a new channel for real-time online monitoring of trace water in transformer oil, which holds promise for information perception and intelligent operation of transformers in the power industry.

Two Calcium Coordination Polymers with Multi‐Stimuli‐Responsive Properties

AbstractTwo skeleton isomers, [CaL(H2O)(DMF)2]•DMF (1) (H2L=5‐(1,3‐dioxo‐1H‐benzo[de]isoquinolin‐2(3H)‐yl)isophthalic acid) with a 1 dimensional chain structure and [CaL(DMF)1.72]• (DMF)0.28 (2) with a 2 dimensional layer structure were synthesized. Mechanochromic luminescence studies reveal that 1 and 2 exhibit luminescent red‐shift and blue‐shift respectively under grinding stimuli. The different influence of grinding stimuli on the π⋅⋅⋅π interaction in the two structures are proposed to be the main reason for such different responses. In addition, 1 has a rare broad sensing ability for halogenated hydrocarbons and can distinguish seven halogenated hydrocarbons out of 17 solvents. 1 can also be used for rapid detection of trace water in DMF with a calculated detection limit of 0.0078 v/v %. The relevant recognition mechanism is the decomposition of the structure during the recognition process due to the water instability of the ionic bond. The above results reveal that both compounds have the potential to be used as multi‐stimulus‐responsive materials.

Neomangiferin defect-engineering ZIF-8 for visually differentiating aprotic/protic solvents and real-time sensing trace water

Defective neomangiferin–ZIF-8 with high stability and reversible solvatochromic behavior was fabricated for the visual discrimination of aprotic/protic solvents and detection of trace water.

Liquid and solid-state tunable fluorescent carbon dots for trace water detection.

We synthesized a type of sulfur and nitrogen co-doped carbon dot, which can achieve tunable fluorescence both in solutions and solid matrices, that is dominated by the surface state. Moreover, it can be used to detect trace water in a variety of organic solvents, especially in acetone with a limit of detection as low as 0.042%.